Last month, Mr Armer's company, Armer Farms (NI), was fined $72,000 in the Tauranga District Court for fouling a Bay of Plenty stream.

Mr Armer and wife Dale, worth $200 million, are ranked 49th on NBR's 2012 Rich List and have extensive dairy farming interests in both islands, including a majority shareholding in Dairy Holdings, the country's largest corporate dairy farm business.

In the Senescall Akers statement, Mr Armer says: “For many years I have been, and continue to be, a strong supporter of the New Zealand dairy industry and an advocate for Fonterra’s important work. I will continue to be."

Mr Armer is locked in a High Court battle with Dairy Holdings founder Alan Pye, who is challenging Mr Armer's attempted seizure of control of Dairy Holdings.

Multimillionaire Mr Pye claims Mr Armer broke pre-emptive share rights and took out loans against Dairy Holdings shares he holds in trust on behalf of other parties.

Dairy Holdings owns about 58 farms and has estimated assets of around $600 million.

If you have more information on Colin Armer's resignation, email David Williams.